Retinal light-damage is studied at low-to-moderate intensities (10 to 1500 lux) in pigmented and albino rats. Immediate goals include: 1) Study the superior retina and determine why it is so sensitive to damage compared with the inferior; 2) Study the effects of age on the severity and irreversibility of light-damage; 3) Re-investigate the action spectrum of low intensity damage; 4) Begin studies of the regenerability of visual pigment in normal and light-damaged animals. Some of these studies (2 and 3) are parametric in nature and are aimed at quantification of the conditions which lead to damage. Results to date indicate that conditions must be very carefully controlled if reproducible data are to be obtained. The other goals (1 and 4) represent the beginnings of an attempt to understand the mechanisms of light-damage. Two hypotheses are proposed: a) Light-adaptation and light-damage lie on a continuum. The former becomes the latter if it is prolonged. b) Light-adapted photoreceptors are anaerobic and cannot tolerate this inefficient state over long periods of time. Testing of these hypotheses may begin during the coming year.